Speed of motion of a short-circuit arc in an insulated conductor

The paper deals with different scenarios of electric arc discharge propagation in the ITER tokamak toroidal magnet conductor. Estimates are obtained for the rate of discharge propagation along an insulated conductor and the conditions under which the conductor is cut by a direct current arc with typical values of 10–80 kA. The modes of a vacuum arc and normal and high-pressure arcs are considered. The analysis was based on steady-state heat- and mass-transfer equations in a combination with the model of evaporation of the Knudsen–Langmuir surface.